U.S. patent application number 09/972581 was filed with the patent office on 2002-05-02 for above deck unit for automatic identification system.
Invention is credited to Goto, Naohisa, Haga, Masanori, Takayama, Masaki, Yokoyama, Naoki.
Application Number | 20020050952 09/972581 |
Document ID | / |
Family ID | 18804957 |
Filed Date | 2002-05-02 |
United States Patent
Application |
20020050952 |
Kind Code |
A1 |
Takayama, Masaki ; et
al. |
May 2, 2002 |
Above deck unit for automatic identification system
Abstract
An above deck unit for an AIS (automatic identification system)
is externally installed on a ship. The above deck unit includes a
radio circuit and an associated antenna for transmitting and
receiving a message, a position detector and an associated antenna,
associated controller and power supply, and a container for storing
these elements. An inboard transmission path, e.g., a cable,
connects the outdoor unit for the AIS and an AIS display serving as
an interface means for the crew. A signal to be transmitted through
the inboard transmission path is a processed, for example, an
amplified signal, rather than an unprocessed output of a VHF
antenna. Therefore, problems of signal loss or degradation along
the inboard transmission path are unlikely to occur. Because the
unit is incorporated within a single container, it can easily be
installed and transferred. With this antenna complex, it is also
possible to suppress interference between antennas.
Inventors: |
Takayama, Masaki; (Tokyo,
JP) ; Yokoyama, Naoki; (Tokyo, JP) ; Haga,
Masanori; (Tokyo, JP) ; Goto, Naohisa; (Tokyo,
JP) |
Correspondence
Address: |
Matthew E. Connors
Samuels, Gauthier, Stevens & Reppert
Suite 3300
225 Franklin Street
Boston
MA
02110
US
|
Family ID: |
18804957 |
Appl. No.: |
09/972581 |
Filed: |
October 5, 2001 |
Current U.S.
Class: |
343/702 ;
343/709 |
Current CPC
Class: |
G01S 19/35 20130101;
H01Q 1/34 20130101; H01Q 9/0407 20130101; H01Q 9/32 20130101; H01Q
21/28 20130101; B63B 49/00 20130101; G01S 19/14 20130101; G01S
19/36 20130101 |
Class at
Publication: |
343/702 ;
343/709 |
International
Class: |
H01Q 001/24; H01Q
001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 27, 2000 |
JP |
2000-328039 |
Claims
What is claimed is:
1. An above deck unit for an automatic identification system
contained in shipborne facilities installed on a ship, the
shipborne facilities being part of the automatic identification
system, comprising: a container, a messaging antenna mounted on the
surface of said container and used for transmitting and receiving a
message, said message being communicated automatically in a
wireless manner between ships or between a ship and a coast
station, said message containing static information, such as a name
of a ship, and dynamic information, such as a current position of
the ship, a radio circuit stored in said container and using said
messaging antenna for transmitting and receiving said message, said
container and said radio circuit being externally installed on the
ship so as to allow said transmitting and receiving of said message
to and from another ship or a coast station, and a controller
installed in said container or installed externally, independently
of said container for controlling said transmitting and receiving
operations of said radio circuit, said controller supplying
information to be contained in said message to the other ship or
the coast station to said radio circuit, thereby transmitting said
message from said radio circuit, said controller outputting
information contained in said message received by said radio
circuit from the other ship or the coast station through an inboard
transmission path, thereby supplying information to be provided to
a crew to an interface means for the crew connected via said
inboard transmission path.
2. An above deck unit for the automatic identification system
according to claim 1, further comprising a measuring device stored
in said container for generating the dynamic information to be
transmitted.
3. An above deck unit for the automatic identification system
according to claim 2, further comprising a positioning antenna
mounted on the surface of said container and used for receiving
said position signal, and wherein said measuring device includes a
radio determination device for generating the dynamic information
including a position of the ship based on a navigation signal
received in a wireless manner.
4. An above deck unit for the automatic identification system
according to claim 3, wherein said positioning antenna is a planar
antenna arranged on the outer surface of said container, said
outdoor unit for the automatic identification system includes a
radome covering said positioning antenna, and said messaging
antenna is a whip antenna having a plane of polarization extending
orthogonal to that of said planer antenna, said whip antenna having
an end passing through said radome and extending externally.
5. An above deck unit for the automatic identification system
according to claim 4, wherein said outdoor unit further includes a
cable for connecting said whip antenna with said radio circuit, and
said planar antenna and said whip antenna have a different radiator
and share a grounded conductor supplying a ground potential, said
cable connecting said whip antenna with said planar antenna
configured such that said grounded conductor serves as the grounded
conductor for both said planar antenna and said whip antenna.
6. An above deck unit for the automatic identification system
according to claim 5, wherein said container includes a conductive
part occupying a part of the surface of said container for
electrically conducting with the surface of said planar antenna,
said conductive part serving as the grounded conductor of said whip
antenna.
7. An above deck unit for the automatic identification system
according to claim 5, further comprising a coaxial cable connecting
said whip antenna and said radio circuit, and, a coaxial connector
for detachably connecting said whip antenna and said radio circuit,
said coaxial connector having an outer conductor connected to the
grounded conductor of said planar antenna.
8. An above deck unit for the automatic identification system
according to claim 5, wherein said cable is a coaxial cable having
an outer conductor and an inner conductor insulated from said outer
conductor, said outer conductor being connected with said grounded
conductor and said inner conductor being connected with said
radiator of said whip antenna, to thereby connect said whip antenna
with said radio circuit.
9. An above deck unit for the automatic identification system
according to claim 8, wherein said coaxial cable has a tip end part
where said outer conductor is removed for a predetermined length
and said inner conductor is connected with said radiator of said
whip antenna, and said tip end part of said inner conductor serves
as the radiator continuing from said radiator of said whip
antenna.
10. An above deck unit for the automatic identification system
according to claim 8, wherein said planar antenna has a through
hole penetrating through said grounded conductor, and said whip
antenna has an in-container extension conductor passing through
said through hole and extending into said container, said
in-container extension conductor being a part of said radiator of
said whip antenna or being a conductor connected with said radiator
of said whip antenna, said in-container extension conductor
connecting said inner conductor of said coaxial cable with said
radiator of said whip antenna at a position closer to the interior
of said container from said through hole of said planar antenna,
said inner conductor of said coaxial cable provided in the interior
of said container and extending from said through hole.
11. An above deck unit for the automatic identification system
according to claim 4, further comprising a coaxial cable connecting
between said whip antenna and said radio circuit, and a coaxial
connector detachably connecting between said whip antenna and said
radio circuit, wherein said radome has a through hole for
externally extending one end of said whip antenna to the outside of
said radome, and said coaxial connector seals said through hole in
a watertight manner.
12. An above deck unit for the automatic identification system
according to claim 1, wherein said container is partly formed by a
heat conductor, and said outdoor unit for the automatic
identification system includes a heat generating member stored in
said container for generating heat during operation, said heat
generating member being arranged in contact with or in proximity to
the inner surface of said container so as to allow heat to be
discharged to surrounding air via said container.
13. An above deck unit for the automatic identification system
according to claim 1, further comprising a long range antenna
mounted on the surface of said container and used for wireless
communications of a long range aiding signal, and a long range
aiding device stored in said container and using said long range
antenna for transmitting and receiving said long range aiding
signal, wherein said controller permits said long range aiding
device to transmit a portion of the information supplied from said
interface means for the crew via said inboard transmission path as
said long range aiding signal, while supplying said long range
aiding signal received by said long range aiding device to said
interface means for the crew via said inboard transmission
path.
14. An above deck unit for the automatic identification system
according to claim 1, further comprising a connector for detachably
connecting the elements stored in said container with said inboard
transmission path, and a power supply means for feeding power to
the elements stored in said container, wherein said power supply
means is formed by one or a combination of one or more of a
connector for connecting the elements stored in said container to
an external power supply, a cell stored in said container for
supplying a discharge output of said cell as a power source to the
elements stored in said container, and a generator means associated
with said container for supplying a generated power of said
generator means to the elements stored in said container.
15. A shipborne facility for an automatic identification system,
comprising: an above deck unit for an automatic identification
system according to claim 1, said interface means for the crew, and
said wired or wireless inboard transmission path.
16. A ship, comprising: the shipborne facility for the automatic
identification system according to claim 15, wherein said ship
sails by obtaining a name, a position, etc. of another ship from
that ship or from a coast station by transmitting and receiving
said message.
17. A waterborne complementary unit for an automatic identification
system installed on a waterborne structure arranged fixedly in a
water area or a floating object floating on the water, comprising:
a container, a messaging antenna mounted on the surface of said
container and used for transmitting and receiving a message, a
radio circuit stored in said container and using said messaging
antenna for automatically transmitting and receiving said message
to and from a ship or a coast station, and a controller for
controlling said transmitting and receiving operations of said
radio circuit, said controller supplying information to be
contained in said message destined for the ship or the coast
station to said radio circuit, wherein said waterborne
complementary unit for the automatic identification system
transmits the static or the dynamic information, such as the
current position, concerning said waterborne structure or said
floating object by transmitting said message.
Description
BACKGROUND OF THE INVENTION
[0001] a) Filed of the Invention
[0002] The present invention generally relates to shipborne
facilities for an automatic identification system (AIS). More
specifically, the present invention relates to an ADE unit for an
AIS, i.e., an outdoor unit capable of being used as an ADE which
together with BDE constitutes the shipborne facilities for the
AIS.
[0003] b) Description of the Related Art
[0004] b1) Introduction
[0005] As disclosed in the Japanese Patent Laid-Open Publication
Nos. H11-326511 and H11-331110, the AIS is a system aimed to
contribute to safe and efficient navigation of a ship. To achieve
this, the AIS serves to automatically receive/transmit radio
messages including static and dynamic information between ships or
between a ship and a coast station. In general, the static
information contained in a message would not be changed merely by
the movement of the ship that originates the message or by the
elapse of time. The static information includes items of
information useful for identifying the ship that originates the
message, such as vessel name, IMO (International Maritime
Organization) number, call sign, and so on. The static information
also includes other information relating to the character and
schedule of the current voyage of the ship originating the message.
This information may include the likes of length, width, type,
draft, destination, cargo, etc. of the ship. Unlike the static
information, the dynamic information including the current position
(e.g., longitude and latitude), speed of the ship changes over time
and as the ship moves.
[0006] The AIS consists of coast facilities installed at coast
stations and shipborne facilities mounted on individual ships. To
realize ship-to-ship and ship-to-coast station automatic radio
messaging, the shipborne facilities must include the following
devices.
[0007] First, a circuit and an antenna for performing and
controlling communications of radio messages are required.
[0008] Second, a means for providing a crew of a ship, on which the
facility is installed, with static and dynamic information
concerning their ship and other ships is necessary. This can be
implemented by various display devices, e.g., a CRT and an LCD, and
audio output devices including a speaker, a speech synthesizer, and
so on.
[0009] Third, a means for setting the static information concerning
the ship may be necessary. This can be implemented by independent
input devices, e.g., a keyboard and a pointing device, or other
input devices associated with the display device, such as an
operation panel provided on or beside the screen of the display
device.
[0010] Fourth, a means for obtaining the dynamic information of the
ship by way of, for example, measurement may also be needed.
Examples of devices used for this purpose include a wireless
positioning device, which is best represented by a GPS (global
positioning system) receiver, and various sensors, such as a
gyrocompass, a log, or the like. Alternatively, another GNSS
(global navigation satellite system) may be used in place of, or
together with the GPS. The GPS or the GNSS to be used may be
supported by terrestrial or satellite supplemental signals. One
example is a DGPS (differential GPS) which provides a differential
function using a supplemental signal. An SBAS (satellite based
augmentation system), which is one type of DGPS designed to have
functions of ranging, differential, and integration using satellite
signals, may also be used.
[0011] b2) Shipborne Facilities
[0012] FIGS. 13 and 14 show an example arrangement of
conventionally developed shipborne facilities. In the figures, the
above deck equipment (ADE) consists of an antenna and its
peripheral devices, while the below deck equipment (BDE) includes
devices installed in the residential area or workspaces, such as
the pilothouse, of the crew. In the figures, a broken line
represents the conceptual border line between the ADE and the BDE.
A similar line is used in FIGS. 1 and 12 which will be described
later.
[0013] In the example shown in FIG. 13, the ADE includes a GPS
antenna for PPS (pulse-per-second) 10a, a VHF antenna 10b, and a
GPS antenna for positioning 30a. The example shown in FIG. 14
further includes a long range antenna 50a.
[0014] In the example shown in FIG. 13, the BDE includes an AIS
transponder 10, an AIS display device 20, and a GPS receiver for
positioning 30. The example shown in FIG. 14 further includes a
long range aiding device 50 and an associated interface 50b, and a
gyrocompass 60 and an associated interface 60a.
[0015] As can be seen, various transmission lines are provided
between places where the ADE and the BDE are provided, to connect
between the ADE and the BDE.
[0016] The AIS transponder 10, which belongs to the BDE, includes a
VHF radio circuit 10c, a controller 10d, and a GPS receiver for PPS
10e, as shown in FIG. 15. It also has a power supply or the like
which is not shown. The VHF radio circuit 10c carries out the
above-mentioned messaging and consists of a TDMA transmitter 10f, a
TDMA receiver log, a DSC receiver 10h, and other components. The
TDMA transmitter 10f and the TDMA receiver 10g are circuits for
receiving and transmitting the message according to the TDMA
(time-division multiple-access) method. The TDMA transmitter 10f
uses the VHF antenna 10b to transmit both static and dynamic
information concerning the ship on which the AIS transponder 10 is
installed to other ships or to coast stations. The TDMA receiver
10g uses the VHF antenna 10b to receive from other ships static and
dynamic information concerning them. In addition, the DSC receiver
10h uses the VHF antenna 10b to receive DSC (digital selective
calling) calls to the ship. It should be noted that, although for
the sake of simplicity of drawing, each of the transmission and
receiving functions is represented by a single block, additional
transmission and receiving systems would be provided as needed in
practice according to international law or protocol.
[0017] The controller 10d controls transmitting/receiving
operations of the VHF radio circuit 10c as described below. First,
when the TDMA receiver 10g installed on a first ship receives
static and dynamic information concerning, e.g., of another ship,
the controller 10d correspondingly causes the TDMA transmitter 10f
to transmit the static and dynamic information concerning the first
ship. To succeed in this messaging operation, synchronization in
terms of timing of TDMA time slot must be established between the
two ships. To do this, the GPS receiver for PPS 10e uses the GPS
antenna 10a to receive a navigation message from a GPS satellite
which is in orbit around the earth and, based on received data,
derive a reference clock to generate a PPS signal. According to the
PPS signal supplied from the GPS receiver for PPS 10e, the
controller 10d controls the operation of the VHF radio circuit 10c
to synchronize the operation of the VHF radio circuit 10c, such as
the timing of the TDMA slot, with that of other ships. To secure a
precise reference clock, the signal path connecting the GPS
receiver for PPS 10e and the controller 10d should be as short as
possible in order to suppress any delays along the signal path. In
consideration of this, the receiver for PPS 10e is installed inside
the AIS transponder 10.
[0018] The controller 10d receives the static and dynamic
information concerning its own ship and supplies this information
to the TDMA transmitter 10f to be delivered to other ships. The
static information concerning the ship is set in advance in the
hardware of the controller 10d, or stored therein in a nonvolatile
manner. Alternatively, it may also be possible for a crewmember or
some other person to set such information at a particular time
before departure of the ship, by operating an operation section
associated with the AIS display 20. The operation section may be
formed by such devices as buttons beside the display screen, a
touch panel on the screen, or an associated keyboard. Pieces of the
dynamic information of the ship regarding the current position
(latitude and altitude), the sailing speed of the ship, etc. can be
obtained from the GPS receiver for positioning 30. The GPS receiver
for positioning 30 receives a signal from a GPS satellite using the
GPS antenna 30a and, based on the received information, carries out
predetermined positioning operations. The information concerning
the heading of the ship, which is included in the dynamic
information, may be obtained from the gyrocompass 60. Various
sensors and devices, including ones not described herein, can be
used to acquire the dynamic information. If the GPS receiver for
PPS 10e serves as the GPS receiver for positioning 30, the external
GPS receiver may be eliminated.
[0019] The controller 10d displays on the screen of the AIS display
20 items of information corresponding to the static and dynamic
information concerning other ships received by the TDMA receiver
10g from other ships or the like, preferably alone with static and
dynamic information concerning the ship on which the AIS
transponder 10 is installed. In principle, various feasible display
styles include the likes of marking positions of other ships on the
screen according to a two-dimensional coordinate system; displaying
near the marked positions static information, such as the name of
the ship, or the dynamic information, such as the heading of the
ship; plotting the trail of other ships by accumulating and
correlating previously obtained pieces of dynamic information;
superimposing a radar image obtained from a radar device (not
shown); superimposing an electronic chart for an ECDIS (Electronic
Chart Display and Information System) retrieved from a storage
device (not shown); displaying positional relationships between the
ship and other ship, or between other ships, using auxiliary lines;
and so on.
[0020] Other displaying styles have been devised, such as those
disclosed in, for example, the Japanese Patent Application No.
2000-89902 filed with the Japanese Patent Office by the same
applicant as the present application, and which is incorporated
herein by reference. It should be noted that, although the AIS
display 20 is preferably a dedicated display device, it is in
principle possible to realize the AIS display 20 by conversion of,
or in combination with, other display devices, including those for
radar, ECDIS, a plotter, or the like. The AIS display 20 can also
display the information received by the DSC receiver 10h or the
long range aiding device 50. Examples of the long range aiding
device 50 are communication devices for INMARSAT-C which is the
service provided by the INMARSAT (International Mobile Satellite
Organization), and other communication devices for data
communications/positioning service operated by ORBCOMM (Orbital
Communications Corp.).
[0021] b3) Problem
[0022] Although the shipborne facilities for the AIS have been
reviewed and analyzed heretofore and many improvements have been
proposed, problems remain.
[0023] First, the above-described shipborne facilities use cables
or the like to connect between the ADE and the BDE. Depending on
the size and the structure of the ship on which the facilities are
to be installed, and on the positional relationship between the ADE
and the BDE, the length of the cable could be such that attenuation
loss can not be ignored. In particular, for example, a VHF antenna
generally does not have an internal RF (radio frequency) amplifier,
and this tends to cause a first problem of loss or degradation of
the cable. Further, because the cables pick up noise, a second
problem is that noise is more apparent appears when the cables are
long (a second problem).
[0024] In the above-described shipborne facilities for the AIS,
there is a third problem that multiple antennas and cables, and the
associated labor and laborers for fitting out the ship, are
required when introducing the shipborne facilities for the AIS,
which complicates the installation. Depending on the relative
positional relationships of respective antennas, interference or
dead zone can occur in the transmitting/receiving output of each
antenna, which is a fourth problem.
[0025] Further, in a case where the BDE devices such as the AIS
transponder and the AIS display are transferred from one ship to
another ship, work such as cutting the cable connection between the
ADE with the BDE on the first ship, transporting to and installing
on the second ship the removed BDE, and connecting the BDE with the
ADE which is already installed on the second ship, is necessary.
This makes it very difficult to adopt a portable, efficient, and
economical usage style, such as the time sharing of a single BDE by
several ships which do not sail simultaneously, which is a fifth
problem. Also, there is a sixth problem in that there is increasing
possibility of an error in cable connection when introducing or
transferring BDE devices, because multiple cables are usually used
for the connection of the ADE and the BDE.
[0026] In addition to the ADE side, the BDE side also has problems.
First, multiple devices must be installed for the BDE, including
the AIS transponder for communicating messages, an interface means
for the crew, such as the AIS display, which provides information
to the crew or is a setting means used by the crew; a positioning
device, such as a GPS receiver, for acquiring dynamic information
concerning the ship; and so on. Further, a large space is required
in which to install these devices, and cable wiring associated with
these devices also requires a large space. When introducing the
shipborne facilities for the AIS to a relatively small ship having
limited onboard space, the large volume requirement of the devices
and cables is a seventh problem. An eighth problem is that it is
bothersome to wire cables for connecting respective devices of the
BDE.
[0027] It is possible to eliminate the external GPS receiver by
allowing the internal GPS receiver for PPS stored in the AIS
transponder to be used for positioning, especially by acquiring
certification and authorization from a particular authority in
charge, whereby the space to be occupied by the BDE and the
associated cables can be reduced. It is also possible, in
principle, to integrate the AIS transponder with the AIS display to
form the BDE which is to be called an integrated AIS display
transponder. This alleviates the inconvenience of laying cables in
the BDE. However, such an integrated AIS display transponder
results in a large volume apparatus, leading to a ninth problem of
difficulty in transportation and installation.
[0028] With either multiple devices or large devices, there is a
tenth problem in that it is difficult to mount the AIS facilities
on a small floating device, such as a buoy. When connecting with
the long range aiding device or the gyrocompass, it is necessary to
also provide for each device an interface in order to compensate
for different specifications. This not only enlarges and
complicates the structure, but also increases the difficulty of
wiring, creating an eleventh problem.
SUMMARY OF THE INVENTION
[0029] The present invention is directed to reducing loss or
degradation of signals traveling through cables; to improving the
anti-noise characteristic of the cables; to reducing the number of
steps, cost, and space required for laying, transferring, and
wiring cables and instances of erroneous wiring; to preventing
occurrence of interference and dead zone among antennas; and to
realizing downsizing, integration, a wider range of installable
ships, and an extended facility usage.
[0030] To achieve the above objects, the present invention is based
on a novel basic concept for constituting the shipborne AIS
facilities. Specifically, heretofore proposed and developed
shipborne AIS facilities are constituted according to a basic frame
and design concept in which most of the facilities are installed as
the BDE, and the BDE is the connected with the ADE through cables
or the like. To solve the above-described problems attributable to
such a basic frame concept, the present invention boldly abandons
such a basic frame concept, which is common practice, and perhaps
even "common sense", to those who practice the art. The present
invention provides an apparatus capable of being "an outdoor unit
for the AIS" or "an ADE unit for the AIS" by unitizing the elements
belonging to the ADE in accordance with a particular configuration.
Essentially or additionally, the ADE unit for the AIS according to
the present invention has characteristics as described below.
[0031] First, the ADE unit for the AIS according to the present
invention is used in the AIS. The AIS is a system for automatically
messaging in a wireless manner static information, such as the name
of the ship, and dynamic information, such as the current position
of the ship between ships or between a ship and a coast station.
The ADE unit for the AIS according to the present invention forms a
part of the shipborne facilities to be mounted on a ship. The ADE
unit according to the present invention is externally installed on
a ship to enable communication with other ships or the coast
station. Here, externally installed primarily refers to being
installed on an area of the ship exposed to the environment, such
as a deck, but also includes semi-exposed spaces under a cover or a
deckhead. In addition, the ADE unit for the AIS according to the
present invention provides information to be supplied to the crew
via a wired or wireless inboard transmission path to the interface
means for the crew. The interface means for the crew may be a fixed
or portable device.
[0032] The above deck unit for the AIS according to the present
invention includes a container for storing various circuits. An
antenna, such as a messaging antenna, is mounted on the surface of
the container, which is, e.g., a VHF antenna, used for
transmitting/receiving messages. The circuits stored in the
container include i) a radio circuit for transmitting/receiving the
message using the messaging antenna, and ii) a controller for
regulating transmitting/receiving operations carried out by the
radio circuit. The controller serves, for example, to supply
information to be included in the message broadcasted to or
destined for other ships or the coast station to the radio circuit,
and to supply information included in the message received by the
radio circuit from other ships or the coast station to the
interface means for the crew through the inboard transmission path.
Herein, the nature of the inboard transmission path is largely
different from that under the conventional developmental idea. The
conventional art requires the radio circuit and the controller to
be placed on the BDE side. As such, conventionally, an inboard
transmission path is provided for connecting between the antenna
and the radio circuit. In contrast, according to the present
invention, the elements that are conventionally included in the
BDE, such as the radio circuit and the controller, are provided on
the ADE side. Therefore, the inboard transmission path of the
present invention serves primarily as a transmission path between
the controller and the interface for the crew.
[0033] By transferring this portion of the devices or circuits,
which conventionally are included in the BDE, to the ADE, the
present invention allows the number of channels of the inboard
transmission path between the ADE and the BDE to be decided
independently of the number of antennas. In other words, even if
multiple antennas are provided associated with the ADE, it is
sufficient to provide only one inboard transmission path, e.g., a
cable, between the ADE and the BDE (a solution to the third
problem). Moreover, even if the inboard transmission path is
implemented by a wired cable, it is unlikely that an erroneous
connection or the like of the cable will occur during installation,
transfer, or the like of the shipborne facilities, because only one
cable is needed for the inboard transmission path between the ADE
and the BDE (a solution to the sixth problem). This would also
facilitate the adaptation of a portable, efficient, and economical
usage style (a solution to the fifth problem).
[0034] According to the present invention, the circuits placed on
the ADE side are stored in a single container, and an antenna, such
as a messaging antenna, is mounted on the surface of the container.
In the above-described conventional arrangement, the inboard
transmission path between the ADE and the BDE serves as the
transmission path for connecting between the antenna and the radio
circuit. In the present invention, such an antenna-to-radio circuit
transmission path corresponds to the transmission path for
connecting the surface and the interior of the container.
Therefore, the transmission path between the antenna and the radio
circuit is short and is enclosed, for the most part, in the
container, which minimizes the chance of generating loss or
degradation and entering noise. A signal transmitted between the
ADE and the BDE of the present invention is a processed signal
passed through the radio circuit or the controller, such as a
digital signal or a video signal carrying data, rather than a
signal of a generally high frequency and a faint power, such as a
signal transmitted between the antenna and the radio circuit. This
suppresses noise entry, loss, and degradation of the signal in the
inboard transmission path between the ADE and the BDE to a level
low enough to be ignored or easily compensated for (a solution to
the first and second problems).
[0035] In the present invention, only the interface means for the
crew, such as a display and an audio output device, need be
provided for the BDE. It is unnecessary to provide multiple devices
for the BDE, or connect between such devices. This realizes
advantages, such as reducing the space occupied by the BDE (and the
associated means for connecting between the BDE and the ADE or
other devices of the BDE), facilitating installation on a
relatively small ship (a solution to the seventh problem), and
eliminating the connection lines among respective devices of the
BDE (a solution to the eighth problem). Further, the size of the
interface means itself for the crew does not increase (a solution
to the ninth problem).
[0036] The container stores a measuring device for generating the
dynamic information to be transmitted, such as a GPS receiver, a
gyrocompass, or a GPS gyro, in addition to the radio circuit, e.g.,
the VHF radio circuit, and the controller. One type of such
measuring device stored in the container is a radio determination
device, such as the GPS receiver or the GPS gyro, which generates
the dynamic information including the position of the ship based on
a navigation signal received through the ether. Since the radio
determination device is stored in the container, it is also
preferable to mount a positioning antenna, which is used for
receiving the navigation signal, on the surface of the container.
Although the gyrocompass may be used for detecting the heading of
the ship, it is sometimes necessary to detect and integrate the
gyrating speed of the bow based on the output of the gyrocompass.
With the GPS gyro, it is sufficient to couple positioning results
of a plurality of GPS receivers. It should be noted that the GPS
gyro is a sensor which detects a bearing or an inclination of an
object, e.g., a ship, on which the GPS gyro is mounted, based on
the signal from multiple GPS receivers which are fixedly positioned
relative to each other.
[0037] When it is desired to adopt the configuration wherein the
messaging antenna and the positioning antenna are mounted on the
surface of the container and the radio circuit, the controller, the
position detector, and so on are stored in the container, an
antenna complex is preferably provided, by integrating the
messaging antenna and the positioning antenna. One approach is to
install an antenna complex that consists of a planar antenna and a
whip antenna. The planar antenna, such as a patch antenna, may be
provided on the outer surface of the container as the positioning
antenna. Because the planar antenna used in the GPS, for example,
is susceptible to weather, dust or sea conditions, it is usually
protected by a radio-permeable, nonmetallic radome. A whip antenna
may be used as a messaging antenna, and is comprised of a pole-like
conductor having an approximately 1/4 wavelength as a radiator. The
whip antenna is arranged such that one end of the radiator extends
externally through the radome and such that the radiator fits to
the radome of the planar antenna. With this antenna structure, it
is possible to provide multiple antenna functions by effectively
using the container, especially the limited surface area of the
container, to further minimize the ADE unit for the AIS.
[0038] One example of such an antenna complex suitable for
implementing the present invention is disclosed in Japanese Patent
Laid-Open Publication No. Hei 10-247815 by Koshio and Goto. In this
publication, it is disclosed that the planar antenna is positioned
relative to the whip antenna in such a manner that the planes of
polarization of both antennas are arranged orthogonal to each
other, in an attempt to avoid any interference. The cable
connecting between the whip antenna and the radio circuit is also
connected to the planar antenna so that the planar antenna and the
whip antenna share a common grounded conductor. In this way, it is
possible to substantially eliminate the influence of the presence
of the planar antenna on the characteristic of the whip antenna,
while relatively easily correcting and compensating for the
influence of the presence of the whip antenna on the characteristic
of the planar antenna (a solution to the fourth problem).
[0039] In some preferred embodiments of the present invention, the
above-described antenna structure is used with a container of which
at least part is formed by a conductor. The grounded conductor of
the planar antenna is connected to the conductive part of the
container to provide a grounded conductor for the whip antenna,
thereby securing and enlarging the grounded surface of the whip
antenna. In addition, at least one other portion of the container
is formed by a thermal conductor placed in contact with or in
proximity to the inner surface of the container in a manner that
heat generated by a heating member (e.g., a radio circuit having an
amplifier which generates heat during its operation) stored in the
container is transmitted to the surrounding air via the container.
This allows heat to be radiated and cooled by natural cooling in
place of forced cooling, thereby simplifying the structure and
realizing stable and highly reliable circuit operations.
[0040] In some preferable embodiments of the present invention, the
whip antenna is connected to the radio circuit by a coaxial cable,
where a coaxial connector is used for realizing a detachable
connection. This arrangement increases the exchangeability of the
whip antenna, which facilitates maintenance and replacement of the
whip antenna and simplifies new installation and transfer
procedures of the ADE unit for the AIS. The coaxial connector can
be fixed primarily at a point of the planar antenna where a through
hole is formed, and secondarily at a point of the radome where
another through hole is formed. By attaching the coaxial connector
at either point, the region where the through hole is formed in
either the planar antenna or the radome (corresponding to the base
part of the whip antenna herein) is mechanically forced by the
coaxial connector, giving the unit an increased resistance to
strong vibrations. When the coaxial connector is provided at the
first point, an outer conductor of the coaxial connector may be
connected to the grounded conductor of the planar antenna to secure
and enlarge the grounded surface of the whip antenna.
[0041] At the second point, the coaxial connector is preferably
fixed so as to seal the through hole of the radome in a watertight
manner, realizing a simple watertight arrangement without packing
rubber or a gasket. With the coaxial connector fixed to the second
point, it is unlikely that the coaxial connector would cast a
shadow on the planar antenna, compared to the coaxial connector at
the first point, and it is very unlikely that the coaxial connector
would obstruct the capturing or tracking of a satellite by the
planar antenna. In addition, if the coaxial connector is provided
at the first point, an inner diameter of the through hole to be
formed in the planar antenna must be determined corresponding to an
outer diameter of the coaxial connector, which forcedly increases
the inner diameter of the through hole. With the coaxial connector
provided at the second point, the inner diameter of the through
hole can be made smaller, because it can be determined based on the
outer diameter of the coaxial cable. A small inner diameter of the
through hole may increase the design freedom of the planar antenna,
which helps widen the frequency band available for the planar
antenna.
[0042] Alternatively, in other preferable embodiments of the
present invention, the whip antenna is connected to the radio
circuit by the coaxial cable without using the coaxial connector,
so as not to cast a shadow on the planar antenna. To realize this
arrangement, the conductors of both the planar antenna and the whip
antenna are arranged so that the grounded conductor of the planar
antenna serves as the grounded conductor of the whip antenna, as
described above. When connecting the coaxial cable extending from
the radio circuit, the outer conductor of the coaxial cable from
the radio circuit is connected to the grounded conductor of the
planar antenna, and an inner conductor of the coaxial cable is
connected to the radiator of the whip antenna. This not only
abolishes the coaxial connector, but also secures the grounded
surface of the whip antenna, suppresses the inner diameter of the
hole in the planar antenna, and so on.
[0043] Examples of this type of arrangement include a first
arrangement wherein the outer conductor of the coaxial cable is
partly removed in advance for a predetermined length from a tip end
of the coaxial cable, and the tip end of the inner conductor of the
coaxial cable where the outer conductor is removed is connected to
one end of the radiator of the whip antenna. Alternatively, in a
second arrangement, the radiator of the whip antenna or any
conductor connected therewith is extended toward the inside of the
container via the through hole of the planar antenna, and the inner
conductor of the coaxial cable is connected to the radiator of the
whip antenna directly or indirectly. In these arrangements, the
inner conductor of the coaxial cable partly serves as a radiator
continuing from the radiator of the whip antenna. Optimally, the
inner diameter of the through hole of the planar antenna can be
reduced to the size of the outer diameter of the coaxial cable
(when the coaxial cable penetrates through the hole) or to the size
of the outer diameter of the inner conductor of the coaxial cable
(when the part of the coaxial cable where the outer conductor is
removed penetrates through the hole). This enlarges the scope of
design freedom of the planar antenna.
[0044] In particular, the inner conductor of the coaxial cable is
only present inside the container in the second arrangement when
viewed from the planar antenna, so that replacement of the planar
antenna is simplified. In the first arrangement, because the joint
between the coaxial cable and the whip antenna exists external to
the container when viewed from the planar antenna, the connection
is made by a non-reversible connecting means, such as soldering.
Alternatively, the inner conductor of the coaxial cable may be
connected to the radiator of the whip antenna by a removable
connector at the cost of casting a shadow on the planar antenna. In
contrast, the connection of the second arrangement is made by
placing a connector for directly or indirectly connecting between
the coaxial cable and the whip antenna inside the container when
viewed from the planar antenna. Therefore, soldering is not
necessary, and a detachable connection can be realized without
casting a shadow on the planar antenna. In the first arrangement, a
part of the inner conductor is exposed near the tip end of the
coaxial cable and used substantially as a part of the whip antenna.
This part of the inner conductor is mechanically fragile and more
likely to be cut off than other parts of the inner conductor. The
second arrangement need not include such a fragile part, making
unlikely any disconnection of the inner conductor leading to a
disorder of the whip antenna.
[0045] In embodying the ADE unit for the AIS according to the
present invention, it is possible to incorporate the wireless
communication function of various long range aiding devices, such
as the devices associated with the INMARSAT-C or ORBCOMM, into the
container which is placed outdoors, in addition to the messaging
function of, e.g., VHF and the positioning function of the GPS,
gyros, the GPS gyro, or the like. Specifically, a long range
antenna used for wireless communication of long range aiding
signals is mounted on the surface of the container which stores the
radio circuit, the controller, and so on, while the long range
aiding device for communicating the long range aiding signals using
the long range antenna is installed inside the container. It should
be noted that installed in the container is a portion of the long
range aiding device mainly related to the wireless communication,
and that another portion of the device mainly related to the
interface for the crew is formed by the above-described interface
means for the crew or provided as a separate interface means
associated therewith. The controller allows the long range aiding
device to transmit some portions of the information supplied from
the interface means for the crew via the inboard transmission path
as the long range aiding signal, while supplying the long range
aiding signal received by the long range aiding device to the
interface for the crew via the inboard transmission path.
[0046] As described above in connection with FIG. 14, when the AIS
transponder is newly installed on a certain ship, and it is desired
to connect the AIS transponder with an existing or any
simultaneously introduced long range aiding device, a device for
interfacing between the devices must also be introduced. In
contrast, if at least a portion of the long range aiding device
mainly related to the signal communications is already incorporated
in the container of the outdoor facilities as described above, it
is only necessary to connect the circuits and elements in the
container to the interface means for the crew, such as a
general-purpose personal computer. In other words, there is no need
to introduce the interface device between the transponder and the
long range device, and the wiring can be simplified (a solution to
the eleventh problem). When the AIS transponder is newly introduced
to a ship having no long range aiding device, it is also possible
to introduce the long range aiding function at a low cost by
introducing the system utilizing the ADE unit according to one
embodiment of the present invention.
[0047] To improve the portableness of the ADE unit for the AIS, it
may be preferable to provide a connector for removably connecting
the elements stored in the container with the inboard transmission
path. The connector, or any connector separately provided for the
power supply, may also be used for feeding power to the elements
stored in the container from an external power supply. The
portableness may further be improved by providing a cell or any
generator means which generates power by discharging or generating
operations inside, or on the surface of, the container.
[0048] The ADE unit for the AIS according to the present invention,
together with the above-mentioned interface means for the crew and
the wired or wireless inboard transmission path, forms a part of
the shipborne facilities for the AIS. The shipborne facilities for
the AIS correspond to the part of the AIS, especially the onboard
part of the AIS, which is the system for assisting the voyage of
ships by communicating messages concerning the names, locations,
etc., of other ships received from them or a coast station and
supplying it to each ship. Therefore, it is assumed that the
present invention is used primarily on ships, but the present
invention is not limited to this application. For example, the
present invention can be implemented as a waterborne complementary
unit for the AIS, such as a unit mounted on a buoy, which is
mounted on a waterborne structure placed fixedly in a certain water
area or a waterborne floating structure. The waterborne
complementary unit for the AIS is provided with a messaging antenna
on the surface of the container for wireless communications of the
message. The container stores the radio circuit for automatically
receiving and transmitting messages from and to ships or a coast
station using the messaging antenna, and the controller for
controlling the receiving/transmitting operations of the radio
circuit and supplying the information to be communicated to the
ships or the coast station to the radio circuit. Thus, the
waterborne complementary unit for the AIS can transmit the static
or dynamic information, such as the current position of the unit,
concerning the waterborne structure or the waterborne floating
structure on which the unit is mounted. Because the unit has a
compact structure wherein one or more circuits and antennas are
incorporated in a single container, the unit can more easily be
mounted on, e.g., a buoy, than those arrangements shown in FIGS. 13
and 14 (a solution to the tenth problem).
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] FIG. 1 is a block diagram illustrating an arrangement of the
shipborne facilities for the AIS, especially the classification of
and the connection between respective devices of the BDE and the
ADE, according to a first embodiment of the present invention;
[0050] FIG. 2 is a schematic sectional view illustrating an
arrangement of an ADE unit for the AIS, especially an arrangement
of respective elements in a container and a location where an
antenna is placed on the surface of the container, according to the
first embodiment of the present invention;
[0051] FIG. 3 is a schematic sectional view illustrating an antenna
structure according to the first embodiment of the present
invention;
[0052] FIG. 4 is a schematic sectional view illustrating an antenna
structure according to a second embodiment of the present
invention;
[0053] FIG. 5 is a top view of a planar antenna according to the
second embodiment of the present invention;
[0054] FIG. 6 is a schematic sectional view illustrating an antenna
structure according to a third embodiment of the present
invention;
[0055] FIG. 7 is a top view of a planar antenna according to the
third embodiment of the present invention;
[0056] FIG. 8 is a schematic sectional view illustrating an antenna
structure according to a fourth embodiment of the present
invention;
[0057] FIG. 9 is a top view of a planar antenna according to the
fourth embodiment of the present invention;
[0058] FIG. 10 is a schematic sectional view illustrating an
antenna structure according to a fifth embodiment of the present
invention;
[0059] FIG. 11 is a top view of a planar antenna according to the
fifth embodiment of the present invention;
[0060] FIG. 12 is a block diagram an arrangement of the shipborne
facilities for the AIS, especially the classification of and the
connection between respective devices of the ADE and the BDE,
according to a sixth embodiment of the present invention;
[0061] FIG. 13 is a block diagram illustrating a conventional
arrangement of the shipborne facilities for the AIS, especially the
classification of and the connection between respective devices of
the ADE and the BDE;
[0062] FIG. 14 is a block diagram illustrating another conventional
arrangement of the shipborne facilities, especially the
classification of and the connection between respective devices of
the ADE and the BDE; and
[0063] FIG. 15 is a block diagram illustrating an internal
structure of a conventional AIS transponder.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0064] The present invention will be described below in terms of
preferred embodiments thereof by reference to the accompanying
drawings.
[0065] (1) First Embodiment
[0066] FIGS. 1-3 illustrate an arrangement of the shipborne
facilities for the AIS according to a first embodiment of the
present invention. The facilities according to the present
invention include an ADE unit for the AIS 40 and an AIS display 20,
which are connected by a wired or wireless inboard transmission
path.
[0067] As described above, the shipborne facilities for the AIS
call for an interface means for the crew in order to provide
information to the crew of the ship on which the facilities are
mounted, by visually displaying the information or providing an
audio output, and to enable setting of static information
concerning the ship. The AIS display 20 is one type of such
interface means and includes a display device, such as a CRT or an
LCD, and various operators, such as buttons, switches, a dial, a
touch panel, a keyboard, a pointing device, etc., which are not
shown.
[0068] As will be described below, various functions served by the
BDE side in the arrangements shown in FIGS. 13-15, such as wireless
communications, positioning and measurement, and signal processing
functions, are covered by the ADE unit for the AIS 40 which herein
belongs to the ADE side. Therefore, a relatively inexpensive and
small universal type device may be used as the AIS display 20. For
example, the AIS display 20 can be realized by various
general-purpose personal computers (PC) including desktop,
notebook, and palm top computers, or personal digital assistants
(PDA). The AIS display 20 can be placed fixedly at the residential
area or workplaces of the crew, or it can be transported or carried
by the crew. There is no need to provide multiple devices as the
BDE, or connect between such devices. This reduces a space occupied
by the BDE necessary for placing the shipborne facilities for the
AIS, which further facilitates the introduction of the facilities
to relatively small ships. This also prevents a disorder caused by
erroneous wiring, because wiring for connecting respective devices
of the BDE is abolished,.
[0069] An inboard transmission path (indicated by a connection line
40 k in FIG. 2) for connecting the AIS display 20 with the ADE unit
for the AIS 40 transmits information, such as part of the static
information concerning the ship entered by the crew by operating
the AIS display 20, or already stored and set in the AIS display
20, to the ADE unit for the AIS 40 from the side of the AIS display
20. The inboard transmission path also transmits necessary
information or signals required to enable, e.g., screen display of
the AIS display 20 from the ADE unit for the AIS 40 to the AIS
display 20. To realize the AIS display 20 by the general-purpose PC
or the like, the inboard, wired or wireless transmission path
between the ADE unit for the AIS 40 and the AIS display 20
preferably conforms to a particular standard and specification
compatible with the PC. If provision of a wired path is desired,
either a fixed or an unfixed cable can be used, according to type
and size of the ship on which the cable is laid (e.g., availability
of space for laying cable), type of the AIS display 20 (e.g., fixed
or portable), and intended use of the shipborne facilities (e.g.,
possibility and frequency of transfer of the facilities).
[0070] Unlike the inboard transmission path between the ADE and the
BDE of the facilities shown in FIGS. 13-15, there is no need to use
a plurality of (or a bundle of) antenna cables as the inboard
transmission path for transmitting signals having a radio frequency
between the ADE unit for the AIS 40 and the AIS display 20. For
example, a cable for transmitting a base band signal serially or in
parallel, or wireless communication by a so-called extremely low
power radio may be used. Wired transmission of the radio frequency
signals can be eliminated because a radio circuit 40e and a
controller 40f are provided on the ADE side, which will be
described later, so that the inboard transmission path between the
ADE and the BDE serves to connect between the controller and the
interface means, rather than between antennas and the radio
circuit. For the same reason, only one inboard transmission path
need be provided between the ADE and the BDE, regardless of the
number of antennas. Therefore, even if a fixed cable is used for
the inboard transmission path, it is possible to suppress the cost
and effort of laying cables, while decreasing the chance of, e.g.,
erroneous connection of the cable during installation or transfer
of the shipborne facilities.
[0071] With such a simplified inboard transmission path between the
ADE and the BDE, as well as the simplification of the BDE (i.e.,
reducing the number of devices in the BDE and eliminating
connections among such devices in the BDE) as described above,
portability of the shipborne facilities is further increased.
Specifically, with the configuration according to the present
embodiment, efficient and economical usage of facilities should by
a plurality of ships is simplified. For example, the shipborne
facilities, especially the ADE unit for the AIS, may be carried by
someone or transferred from a ship that is not scheduled to sail to
another ship. If the facilities of the present embodiment are
introduced to a ship where the cable or the like is already laid
for connecting between the GPS receiver and the GPS antenna, the
existing cable can be used to provide an inboard transmission path
between the ADE unit for the AIS 40 and the AIS display 20, such
that no cost or labor are necessary for laying cables.
[0072] In addition to the reduced number of channels, loss and
noise are reduced, because the transmission path between the ADE
and the BDE can transmit a relatively low frequency signal that is
little affected by noise. Specifically, the signal carried along
the transmission path can be a processed signal passed through the
VHF radio circuit 40e or the controller 40f, rather than an
unprocessed, faint radio frequency signal obtained as an antenna
output. Thus, the risk of occurrence of loss or degradation or
entry of noise in the inboard transmission path between the ADE
unit for the AIS 40 and the AIS display 20 can be suppressed to a
level low enough to be ignored or easily compensated for.
[0073] The shipborne facilities for the AIS also call for the
function of receiving messages of static and dynamic information
concerning other ships from those ships or a coast station, and the
function of transmitting messages of the static and dynamic
information concerning the ship on which the facilities are
installed. Among items of information to be sent to other ships or
the like, the dynamic information concerning the ship must be
detected or entered by some means. The ADE unit for the AIS 40 of
the present invention is characterized by a single container 40a in
which various circuits and devices related to the aforementioned
functions, i.e. the wireless communications and the control of the
message and measuring and positioning for acquiring the dynamic
information concerning the ship. Secondarily, the unit is
characterized as being placed above on the ship so as to transmit
and receive the radio signals to and from other ships and to
receive the signal from the navigation satellite. Thirdly, by
adopting the antenna complex with the container integrated
therewith, the unit can suppress an inter-antenna interference,
noise, and the like, and has a favorable heat radiating
characteristic (which will be described in detail later). It should
be noted that, although no onboard structure for placing the unit
outdoors is shown herein, various structures can be adopted, such
as supporting the unit by a dedicated pole or a pedestal, fixing
the unit by adding supporting members to the existing structure,
tying the unit to or suspending it from the existing structure,
such as a handrail, and so on. The structure to be adopted may be
determined according to the size of the ship, frequency of the
transfer, etc.
[0074] As shown in FIG. 2, the ADE unit for the AIS 40 incorporates
most of the devices shown in FIG. 15 in or on the surface of the
single container 40a.
[0075] Among the devices configured in the container 40a, the VHF
radio circuit 40e corresponds to the VHF radio circuit 10c, the
controller 40f corresponds to the controller 10d, and a GPS
receiver 40g corresponds to the GPS receiver for PPS 10e and the
GPS receiver for positioning 30 of FIG. 15. The GPS receiver 40g
not only generates a PPS signal, but also measures the current
position, the sailing speed, and so on of the ship. The controller
40f supplies to the VHF radio circuit 40e a positioning result
(e.g., the ship is position) from the GPS receiver 40g and a signal
containing the information supplied from the side of the AIS
display 20 via the connection line 40 k. The controller 40f then
causes the VHF radio circuit 40e to perform wireless communications
in synchronism with the PPS signal from the GPS receiver 40g to
handle the received information, and to supply the processed
information to the AIS display 20 via the connection line 40 k.
[0076] FIG. 15 does not show any device corresponding to a power
supply 40h. In the present embodiment, the power supply 40h feeds
power to the devices in and on the surface of the container 40a.
For example, the power supply 40h transforms, rectifies, and
regulates the power provided externally via the connection line 40
k. Alternatively, the power supply 40h may be a primary or
secondary cell, or a solar cell or the like may be placed on the
surface of the container 40a to form the power supply 40h, or one
unit thereof.
[0077] On the surface of the container 40a, a VHF whip antenna 40c
used for communicating messages for the VHF radio circuit 40e, and
a GPS patch antenna 40b used for receiving the navigation signal
(or a navigation message) by the GPS receiver 40g are provided, as
well as a connector (not shown) for connecting the connection line
40 k to the controller 40f and the power supply 40h. The VHF radio
circuit 40e receives and transmits messages using the VHF whip
antenna 40c. The GPS receiver 40g generates the dynamic information
including the position of the ship, based on the navigation signal
received using the GPS patch antenna 40b. The VHF whip antenna 40c
is connected to the VHF radio circuit 40e via a connection line
40i, and the GPS patch antenna 40b is connected to the GPS receiver
40g via a connection line 40j, respectively. The connection lines
40i and 40j are preferably flexible or rigid coaxial cables. In
particular, it should be noted that the length of the connection
lines 40i and 40j, respectively, is significantly shorter than the
antenna connection line shown in FIGS. 13-15, and that these lines
are shielded from the container 40a (when the container 40a is made
of a conductor).
[0078] The VHF whip antenna 40c and the GPS patch antenna 40b are
implemented by an antenna complex, such as, shown in FIG. 3.
[0079] The GPS patch antenna 40b has a circular or rectangular
dielectric substrate 40m (a circular substrate is shown in the
figures). A base conductor 40n serving as a grounded conductor is
provided on one side of the dielectric substrate 40m, while a
circular patch antenna element 40p serving as a radiator is
arranged on the other side of the substrate. Although various parts
and circuits associated with the patch antenna element 40p are not
shown in the illustrated example, those with skill in the art can
easily determine the arrangement of such parts and circuits by
reference to the disclosure of the present invention. The patch
antenna element 40p is fed from the GPS receiver 40g via the
connection line 40j through a coaxial feeding section 40r from the
side of the base conductor 40n, at a predetermined distance apart
from the center of the patch antenna element 40p. In addition, a
through hole is formed in the center of the GPS patch antenna 40b,
and the inner side of the through hole is covered by a conductor
which electrically conducts with the base conductor 40n and the
element 40p, whereby a short pin of the patch antenna element 40p
is formed.
[0080] The radiator or a pole shaped conductor of the VHF whip
antenna 40c extends through a radome 40d and the center of the
element of the GPS patch antenna 40b, wherein the radome 40d is a
cover capable of transmitting radio waves to protect the GPS patch
antenna 40b from weather, dust, and sea conditions. Thus, the
radiator extends from below the patch antenna 40b to above the
radome 40d in FIG. 3. Again, although various parts and circuits
associated with the VHF whip antenna 40c are not shown in the
figure, those skilled in the art can easily determine the
arrangement of such parts and circuits by reference to the present
application. The through hole formed in the radome 40d is sealed in
a watertight manner by a watertight packing 40s formed by rubber or
the like to prevent invasion by rain, the sea, and so on.
[0081] As described above, the through hole formed in the center of
the GPS patch antenna 40b is covered by the conductor and extends
further below to the inside of the container 40a. Although not
shown, a certain supporting structure is adopted for keeping a
predetermined distance between the radiator of the VHF whip antenna
40c and the conductor covering the inside of the through hole of
the GPS patch antenna 40b. This provides a coaxial structure at and
immediately below the through hole formed in the center of the
element of the GPS patch antenna 40b, wherein the radiator of the
VHF whip antenna 40c serves as an inner conductor and the conductor
electrically conducting with the base conductor 40n serves as an
outer conductor. The length of the radiator of the VHF whip antenna
40c is set so that the above-mentioned coaxial structure, i.e., the
part above a coaxial feeding section 40q, is approximately equal to
1/4 of the wavelength used for communication. The coaxial feeding
section 40q is connected to the connection line 40i, which is not
shown. In this embodiment, because the outer conductor or the base
conductor of the coaxial feeding section 40g electrically conducts
with the base conductor 40n, it is secured that the ground surface
of the VHF whip antenna 40c spreads across the entire base
conductor 40n. The ground surface of the VHF whip antenna 40c can
further be increased by making at least part of the container 40a
to be conductive, and fixing the GPS patch antenna 40b to the
container 40a so that the base conductor 40n electrically conducts
with the conductive part of the container 40a.
[0082] In the above-described antenna complex, the plane of
polarization of the VHF whip antenna 40c and that of the GPS patch
antenna 40c are approximately orthogonal to each other, which
prevents interference between the antennas. Because the base
conductor 40n of the GPS patch antenna 40b serves as the grounded
conductor of the VHF whip antenna 40c, it is possible to
substantially eliminate the influence of the GPS patch antenna 40b
on the characteristic of the VHF whip antenna 40c, while correcting
and compensating for the influence of the VHF whip antenna 40c on
the characteristic of the GPS patch antenna 40b relatively easily.
Concerning those points, reference is made to Japanese Patent
Laid-Open Publication No. Hei 10-247815.
[0083] The configuration of this embodiment advantageously reduces
the size of the ADE unit for the AIS 40 the surface area of the
container 40a by adopting the above-described antenna complex,
although multiple antennas are provided. If the container 40a is
made of a metal, for example, it is possible to enlarge the ground
surface of the VHF whip antenna 40c as described above and also to
make use of such an enlarged surface area to promote heat discharge
and cooling of elements within the container 40a. Specifically, as
metals conduct heat and the ADE unit for AIS 40 is installed above
decks, the heat generated inside the ADE unit can be discharged by
natural cooling of the surface of the container 40a. In this
embodiment, heat generating devices stored in the container 40a,
such as the VHF radio circuit 40e having an amplifier and the power
supply 40h having a switching component, are arranged in contact
with or in close proximity to the inner surface of the container
40a (see the arrangement of respective elements shown in FIG. 2),
to thereby enable natural heat discharge to the atmosphere. In this
way, the heat discharging and cooling operation is conducted using
natural air, instead of forced air, thereby simplifying the
arrangement of the device and realizing more stable and reliable
circuit operations.
[0084] Also, the transmission path between the VHF whip antenna 40c
and the VHF radio circuit 40e of this embodiment is much shorter
than the inboard transmission path between the ADE and the BDE in
the examples shown in FIG. 13-15. The transmission path of this
embodiment is also stored in the container 40a made of a metal or
the like. This further reduces the risk of loss or degradation and
minimizes the entry of external noise into the container 40a.
[0085] (2) Second and Third Embodiments
[0086] FIGS. 4 and 5 illustrate a second embodiment and FIGS. 6 and
7 illustrate a third embodiment of the antenna complex according to
the present invention. Here, elements similar or identical to those
in the first embodiment will not be described again, and reference
numerals for such components are not shown in the figures. The
coaxial feeding section 40r is also not shown in these figures.
[0087] In both the second and third embodiments, the connection
line 40i is formed by a coaxial cable 40u, which is connected to
the VHF whip antenna 40c using a coaxial connector 40t. Thus, the
coaxial cable 40u and the VHF whip antenna 40c are removably
connected with each other, allowing the VHF whip antenna 40c to be
temporarily removed during, for example, replacement or transfer of
the antenna, simply by removing the coaxial connector 40t.
[0088] Therefore, the antenna structures according to the second
and third embodiments of the present invention simplify maintenance
and enhance portability compared to the structure of the first
embodiment. In addition, by attaching the coaxial connector 40t to
the through hole of the GPS patch antenna 40b (the second
embodiment) or of the radome 40d (the third embodiment), the base
part of the radiator of the VHF whip antenna 40c is mechanically
forced, which provides anti-vibration characteristics superior to
those obtained with the configuration according to the first
embodiment. Although in the first embodiment a supporting means for
maintaining the distance between the inner and outer conductors at
the coaxial feeding section 40q is required, such a means is not
necessary in the second and third embodiments because of the use of
the coaxial cable 40u.
[0089] The configurations of the second and third embodiments have
respective advantages and disadvantages. In the second embodiment,
the coaxial connector 40t is attached to the through hole of the
GPS patch antenna 40b, so that the coaxial connector 40t is likely
to cast a shadow on the patch antenna element 40p. Namely, the
coaxial connector 40t blocks the signal from the positioning
satellite, which may prohibit the GPS patch antenna 40b from
receiving or acquiring the signal. In the third embodiment, the
coaxial connector 40t is placed away from the patch antenna element
40p, which lessens the risk of casting a shadow of the coaxial
connector 40t on the patch antenna element 40p compared to the
second embodiment.
[0090] The second embodiment calls for the watertight packing 40s
as in the first embodiment. In contrast, the coaxial connector 40t
serves to seal the through hole of the radome 40d in a watertight
manner in the third embodiment, which advantage only reduces the
number of necessary components by abolishing the watertight packing
40s eliminates the need for replacing the packing when the rubber
deteriorates due to aging.
[0091] However, while the second embodiment can secure and enlarge
the ground surface of the VHF whip antenna 40c by rendering the
outer conductor of the coaxial cable 40u, and accordingly of the
coaxial connector 40t, to electrically conduct with the base
conductor 40n, such conduction and connection is difficult in the
third embodiment.
[0092] In the second embodiment, it is necessary to match an inner
diameter of the through hole of the GPS patch antenna 40b with an
outer diameter of the coaxial connector 40t, because of the need
for attaching the coaxial connector 40t. The third embodiment uses
only a small through hole 40w in the GPS patch antenna 40b, as
compared to the second embodiment, because fine coaxial cable 40u
is inserted through the through hole of the GPS patch antenna 40b.
Because through hole 40w is small, the GPS patch antenna 40b
realizes a wider frequency band which improves the degree of design
freedom.
[0093] In the second embodiment, to prevent the conductor on the
inner surface of the through hole from electrically conducting with
the conductor exposed on the surface of the coaxial connector 40t,
an insulator 40v must be provided on the through hole conductor of
the GPS patch antenna 40b. The third embodiment does not require
such the insulator 40v, because the coaxial cable 40u has an
insulative coating.
[0094] (3) Fourth and Fifth Embodiments
[0095] Fourth and fifth embodiments of the present invention are
illustrated in FIGS. 8 and 9 and FIGS. 10 and 11, respectively.
Here, similar or identical elements to those of the first through
third embodiments are not described again and their reference
numerals are not shown in the figures. Also, the coaxial power
supply 40r is not shown in these figures.
[0096] In the fourth and fifth embodiments, the coaxial cable 40u
is used as the connection line 40i, as in the second and third
embodiments. Because the coaxial connector 40t tends to cast a
shadow on the patch antenna 40p, it is eliminated in order not to
prevent the signal acquisition and receiving of the GPS patch
antenna 40b. Instead, the fourth and fifth embodiments uses a
conductive joint 40z which also has a watertight sealing function
and is formed at the through hole of the radome 40d as one element
used to connect the radiator of the VHF whip antenna 40c with the
inner conductor of the coaxial cable 40u.
[0097] In the fourth embodiment, to connect the radiator of the VHF
whip antenna 40c with the inner conductor of the coaxial cable 40u,
a meshed conductor 40x (and a dielectric material) serving as the
outer conductor is removed for a predetermined length from the tip
end of the coaxial cable 40u, and an inner conductor 40y is
extended to the joint 40z via the through hole of the GPS patch
antenna 40b and connected with the joint 40z by soldering. In the
fifth embodiment, a conductive rod 40ab integrated (or connected at
the joint 40z) with the radiator of the VHF whip antenna 40c is
extended inwardly to the container 40a via the through hole of the
GPS patch antenna 40b. The conductive rod 40ab is then connected to
the core wire 40y at a position below the base conductor of the GPS
patch antenna 40b as shown in the figure.
[0098] Thus, the part of the inner conductor 40y where the meshed
conductor 40x is removed, is the fourth embodiment, and the
conductive rod 40ab, of the fifth embodiment, respectively serve as
the radiator of the VHF whip antenna 40c. The inner diameter of the
through hole of the GPS patch antenna 40b can be reduced to about
the size of the outer diameter of the coaxial cable 40u in the
fourth embodiment. Further, the through hole 40ac for the
conductive rod as shown in FIG. 11 can be reduced to the size of
the outer diameter of the conductive rod 40ab added by a small gap
sufficient enough to provide necessary insulation in the fifth
embodiment. This significantly enlarges the available frequency
band (which improves the degree of design freedom). It is necessary
to use an insulator 40ad to preferably insulate between the
conductive rod 40ab and the patch antenna element 40p and, since
the through hole 40ac for the conductive rod is small, the outer
diameter of the insulator 40ad can also be decreased. In FIG. 11,
the insulator 40ad is not drawn to scale.
[0099] In the fourth embodiment, there is a risk of breaking the
solder at a joint between the inner conductor 40y and the radiator
of the VHF whip antenna 40c, or disconnecting the inner conductor
40y where the meshed conductor 40x is removed. In the fifth
embodiment, the inner conductor 40y is not extended into the radome
40d, and the inner conductor 40y may be soldered, if necessary, at
a point (a joint 40aa) lower than the GPS patch antenna 40b.
Therefore, when compared to the fourth embodiment, the fifth
embodiment has an advantage that malfunction, such as the
disconnection of the inner conductor 40y, can be prevented and that
even if such a malfunction occurs, it can be handled easily by
relatively simple procedures.
[0100] Both the fourth and fifth embodiments attempt to increase
and secure the ground surface of the VHF whip antenna 40c by
connecting and fixing the meshed conductor 40x of the coaxial cable
40u with the base conductor 40n of the GPS patch antenna 40b.
Specifically, in the fourth embodiment, the meshed conductor 40x is
soldered near the through hole of the GPS patch antenna 40b so that
the meshed conductor 40x electrically conducts with base conductor
40n or with the inner conductor of the through hole which
electrically conducts with the base conductor 40n. In the fifth
embodiment, the meshed conductor 40x is connected and fixed with
the base conductor 40n at the joint 40aa (simultaneously with
connecting the inner conductor 40y with the conductive rod 40ab) by
using a fastener or a connector or by soldering, in a manner that
the meshed conductor 40x electrically conducts with the base
conductor 40n. In particular, it is possible in the fifth
embodiment to abolish both the inner conductor 40y and soldering of
the meshed conductor 40x. This simplifies the step of attaching the
coaxial cable 40u, and increases the ease of replacement and
maintenance of the GPS patch antenna 40b.
[0101] (4) Sixth Embodiment
[0102] In the above-described embodiments, the VHF whip antenna 40c
and the GPS patch antenna 40b are mounted on the surface of the
container 40a of the ADE unit for the AIS 40, and the VHF radio
circuit 40e, the controller 40f, the GPS receiver 40g, and the
power supply 40h are installed in the container 40a. Alternatively,
the present invention can be implemented by mounting or storing
other antennas and circuits on the surface of or within the
container 40a.
[0103] For example, the gyrocompass or the GPS gyro may be provided
together with the GPS receiver 40g for acquiring the dynamic
information concerning the ship on which the apparatus is
installed. The GPS gyro receives the navigation message from a
navigation satellite at each antenna of multiple GPS antennas
arranged spaced apart from each other. Based on the receiving
result, the GPS gyro performs the positioning operations to
determine the positional relationship of both antennas, to thereby
detect the orientation of a segment between both antennas.
Advantageously, the GPS gyro is less susceptible to magnetic fields
than the gyrocompass, can be used near the North Pole or the South
Pole, can detect the orientation based on the true north instead of
the magnetic north, can detect the inclination of the ship body,
and is handy. With the GPS gyro, the gyro interface and the
calculations for the gyrating speed of the ship become
unnecessary.
[0104] When it is desired to implement the present invention by
applying or modifying the arrangement shown in FIG. 2 so as to
incorporate the GPS gyro, multiple GPS antennas, such as patch
antennas, are arranged spaced apart from each other on the surface
of the container 40a, and then a circuit for calculating the
position and the orientation based on the received output of the
multiple GPS antennas is installed inside the container 40a. The
space required between respective GPS antennas necessary for
constituting the GPS gyro is at most about several tens of
centimeters. The circuit for detecting the orientation based on the
received output of the multiple GPS antennas can be realized by
modifying the GPS receiver shown in FIG. 2 (by adding a particular
operation routine allowing the calculation of positions and
orientations for multiple points). Therefore, even if the GPS gyro
is incorporated, the size of the container 40a increases only
slightly and the transferably between ships of the container is not
significantly affected. It should be noted that the GPS antennas
for the GPS gyro can be used for generating PPS signals and
detecting positions.
[0105] It is also possible to store a part of the long range aiding
device 50, i.e., the circuit related to wireless communications, in
the container 40a and mount the associated antenna 50a on the
surface of the container 40a. By thus configuring the circuits
(especially the controller 40f and the radio circuit related to the
long range aiding function) stored in the container 40a so that a
part of the long range aiding function is incorporated, advantages
similar to those described in connection with the first embodiment
can be achieved. Such advantages include taking the navigation
assistance from, e.g., INMARSAT-C or ORBCOMM, reducing the number
of channels of the inboard transmission path between the ADE and
the BDE compared to the arrangement shown in FIG. 14, facilitating
the installation and transfer of the facilities, and eliminating
long range interface. To incorporate the long range aiding
function, an arrangement such as that shown in FIG. 12, for
example, is used, in which a part of the long range aiding function
corresponding to the interface function for the crew is shown as
the long range aiding device 50c.
[0106] (5) Supplement
[0107] In addition to application to shipborne facilities or the
ADE unit, the present invention can also be applied when it is not
necessary to output received information. Examples of such
applications include a unit for an unmanned station, that is, a
waterborne complementary unit for the AIS which is mounted on a
waterborne structure arranged fixedly in a certain water area, such
as a barge, a lighthouse, or an artificial island, or other
floating structures, such as a buoy.
[0108] When it is desired to implement the present invention in the
above application, the VHF whip antenna 40c can be mounted on the
surface of the container 40a and the VHF radio circuit 40e can be
stored in the container 40a, in order to transmit and receive the
message. With such a configuration, the VHF radio circuit 40e
receives the message from surrounding ships or the coast station
under the control of the controller 40f, while automatically
transmitting a message thereto. The information to be sent includes
the static information for classifying or identifying, or
indicating the position of a particular waterborne structure or
floating structure on which the present invention is installed. If
such a waterborne structure or floating structure is an object
which experiences significant movement, the current position or the
like may be sent as the dynamic information. Because this unit is
compact, wherein one or more circuits and antennas are incorporated
in a single container, it can more easily be mounted on a buoy or
the like than can a unit configured as shown in FIGS. 13 or 14. In
addition, the unit may be operated only by feeding power, because
received information need not be output.
* * * * *